I added a few bolt on mods to my '99 T/A. I replaced the intake manifold with a BBK. I added race headers, ORY and 2.5" exhaust. I have not installed any sensors to compensate for the 2 less oxygen sensors. I did the AIR/EGR delete. I also have not done anything to compensate for those codes.

I was excited to complete the project, but now the engine runs rough. When I first start it, it stalls unless I apply throttle to warm the engine. I have to step on the gas for about 30 seconds for it to run on its own. And then the RPMs will surge from 500-1000.

I cleared the check engine light and ran it for a minute. The only code it threw was P0785, 3-2 Shift Solenoid Circuit Electrical. I don't know what that would have to do with it, if anything. But even if it's a separate issue what could it be? Do I need to run it more to see if more codes pop up?

I recorded a video in the hopes it might help. You can see my lovely assistant spraying starting fluid at the intake manifold to see if there was a leak. It didn't seem to affect the surging from either side he sprayed. You can't really tell in the video, but the engine noticeably shook at times when it would run rougher.


Prior to the changes I made, everything seemed to be running fairly well with the exception of steering wheel vibration when stopped as many others have complained about. What could be the problem? Any advice is appreciated.


*Edit* After the snow melted I was able to drive the T/A for about 30 miles on two trips. It still has the same problem of wanting to stall/rough idle. It surges from about 500-700 RPMs at idle before stalling. Also, when driving the RPMs are much higher than they should be (eg 2k RPM at 45 PMH, 3k RPM at 70 MPH). I bought one of those Diablo Sport tuners thinking I could tune away some of the issues myself, but it seems to have had no effect. Are there any suggestions other than a professional tune? I wasn't expecting that added cost after simple bolt ons.

 

you need to drive it. did you have the battery disconnected when you did these mods? double check all your manifold bolts and everything else for vacumn leaks.

 

I would think you need a tune. Be prepared to get ripped on for installing that intake! LOL.

 

That intake is basicly a metal mold of a ls1 intake. No performance gain and tons of heat soak. Yayyyy

 

I did my research prior to purchase. Many people would disagree with you, but I don't want them posting that here. It's not helpful to my questions.

 

so did u disconnect the battery or what?

 

Dude...your going to have to get a tune to smooth everything out. You made a lot of changes to the car, the ECU is never going to fully compensate for all that.

 

Yes, I disconnected the battery during the process.

 

I've always been able to drive my 98 after bolts on's without a tune initially. The idle went
a little erratic when I did the LS6 intake as well as when I did long tubes. You have to do
a few starts and drive it for the computer to adjust. Mine spiked to 1500 rpms right after I
did my LS6 intake swap..after driving it for a while and a couple of drive cycles it settled down.

But definitely get it tuned soon!

 

I knew everytime i disconnect my battery on my car it takes a couple miles of driving for it to relearn everything. I would recommend taking your car on a nice cruise for maybe 30 minutes then it should find its idle. It will be throwing a ton of codes though. for the air/egr/ rear 02's etc. So just get it tuned asap.

 

Unfortunately I can't drive it right now. Even if I could get it out of the driveway with the snow, they salt the roads here. Hopefully it's an easy fix like relearning idle or a tune. I hooked the code reader up again and got 6 more codes. I was expecting several codes after what I removed.

 

Don't worry about it right now then...mine has done that before after airflow mods. It'll settle down once the computer relearns and corrects from normal driving.

 

After the snow melted I was able to drive the T/A for about 30 miles on two trips. It still has the same problem of wanting to stall/rough idle. It surges from about 500-700 RPMs at idle before stalling. Also, when driving the RPMs are much higher than they should be (eg 2k RPM at 45 PMH, 3k RPM at 70 MPH). I bought one of those Diablo Sport tuners thinking I could tune away some of the issues myself, but it seems to have had no effect. Are there any suggestions other than a professional tune? I wasn't expecting that added cost after simple bolt ons.

 

Check all your vacuum lines. It sounds like you have a vacuum leak some where. You can also check your iac valve. I had one that got partly stuck and did some weird idle changes.

 

You probably still have a vacuum leak or exhaust leak. I couldn't tell from your post but the car will run like crap without front o2 sensors or vacuum/exhaust leak

 

Make sure you didn't accidentally plug your old rear o2 sensors into your headers instead of the front o2 sensors. I didn't think that was possible but I recently had a buddy who admitted to doing it so I guess it can accidentally happen.